1. Field of the Invention
This invention relates to a tamper-evident closure device for a container and is applicable, though not exclusively, to a bottle for sterile water or antiseptic liquid for use in hospitals.
2. Description of the Prior Art
Closure devices are known which comprise a tear tab which normally seals the container but which can be at least partially detached by tearing to leave an opening through which the contents of the container can be removed. One example of such a device is the so-called "ring pull" closure for canned drinks, wherein a ring is attached to a tear tab and by pulling back on the ring the tab can be removed. Similar closure devices have been used on containers for other consumables, such as milk cartons.
An advantage of such devices is that they are "tamper-evident", meaning that they cannot be re-sealed once opened so that any tampering can be detected. This is especially important when it is necessary to detect a possible contamination of the container contents. However, a disadvantage of such closure devices is that they require a relatively large force to start the tear. Further, once the initial tear is made the force required to continue the tear drops substantially so that the tab removal is uncontrolled and liquid spillage often results.
It is an object of the invention to provide an improved closure device which mitigates this problem.